俯冲板块的三维初始化过程研究

Studying the processes of subduction initiation is a key for understanding the Wilson cycle and improving the theory of plate tectonics. Previous studies investigated subduction initiation with geological synthesis and geodynamic modeling methods, discovering that subduction intends to initiate at the transform faults close to oceanic arcs, and that its evolutionary processes and surface volcanic expressions are controlled by plate strength. However, these studies are mainly conducted with 2-D models, which cannot deal with lateral heterogeneities of crustal thickness and strength along the plate interfaces. We plan to extend the 2-D model to a 3-D parallel subduction model with high computational efficiency. With the new model, we study the dynamic controlling factors, morphology evolutionary processes and surface expressions for subduction initiation with lateral heterogeneities of material properties along transform faults and passive margins. The expected results will significantly enhance our understanding for the formation of new trenches and the breakoff processes of subducting plate. The results can also provide geodynamic modeling explanations for the observed remnant slabs in the upper mantle and the surface volcanic expressions.

研究俯冲板块的初始化过程是理解威尔逊循环和完善板块构造理论的关键。之前的研究使用地质学资料和动力学数值模型对板块的初始化过程进行了探讨，发现俯冲带易于在岛弧附近的转换断层产生，其形态演化过程受板块强度控制并在地表产生相应的火山活动。但是这些研究主要使用二维模型,无法研究当沿板块边界存在地壳厚度和强度的不均匀性时俯冲板块的初始化过程。我们计划将之前的二维模型进行拓展以发展出一套高效的三维并行化俯冲模型，并用来研究当相邻板块在沿转换断层或被动大陆边缘存在侧向物质不均匀性时俯冲带初始化的动力学控制因素,以及发生俯冲初始化时三维板块的形态变化过程和地表表现形式。研究结果将增加我们对海沟形成过程和板块断裂变形过程的理解，并能对实际观测到的板块在地幔中的残余形态分布和地表的火山分布特征给出动力学模型解释。